On Syria. I think it's important understand that for. Several years now what we've been saying as -- slowly unfolding. Disaster for the Syrian people. And this is not a situation which we've been. Simply bystanders to what's been happening. My policy from the beginning has been. Present us. Had lost credibility. He. Attacked his own people has killed his own people. Unleashed a military against innocent civilians. And that the only way to bring stability and peace to Syria. Is going to be for Assad to step down and and to move forward on political transition. In pursuit of that strategy we've organized the international community we are the largest humanitarian don't we have worked to strengthen the opposition. We have provided nonlethal assistance the opposition. We have applied sanctions on Syria so. There are -- whole host of steps that we've been taking precisely because. Even suffer from the chemical weapons issues. What's happening in Syria is a blemish on. The international community general and we've got to make sure that we're doing everything we can't protect the Syrian people. In that context what -- also say. Is that the use of chemical weapons would be a game change. Not simply for the United States but for the international community and the reason for that is that we have established international law and international norms. That say when you use. These kinds of weapons. You have the potential. Killing massive numbers of people in the most inhumane way possible. And the proliferation risks are so significant that we don't want -- genie out of the ball. So what I says. The use chemical weapons would be game changer. That wasn't unique to that wasn't a position unique to the United States. And it should have been -- surprise us. And what we now have this evidence that chemical weapons have been used inside of Syria but we don't know. How they were used when they were used. Who -- we don't have -- -- Custody that establishes what exactly happened. And when I am making decisions about. America's national security and the potential for taking additional actions. In response to chemical weapon here's a government struck out the facts. That's what the American people would expect. And if we end up. Rushing to judgment without. Hard effective evidence. -- that we can find ourselves in the position where we can't mobilize the international community to support what we do. There may be objections even among some. People in the region were sympathetic with the opposition if we take action. So. It's important for us to do this -- -- -- -- And what I've said to my team is we've got to do everything we -- to investigate and establish we're. Some certainty what exactly has happened in Syria what is happening in Syria we will use all -- assets and resources that we have. At our disposal. More work where -- The neighboring countries -- -- whether we can establish a clear baseline of facts and we've also called on the United Nations. To investigate. But did the important point I want to make here is that. We already are deeply engage. In trying to bring about a solution in Syria it is a difficult problem. But even its chemical weapons were not being used -- -- We'd still be thinking about tens of thousands of people innocent civilians. Women and children -- been killed by a regime that's more concerned about -- empower -- -- about the well being of speed and so so we are already but deeply invested in trying to find a solution here. What is true though is that if I can establish. In a way that. Not only the United States but also the international community. Feel confident is the use of chemical weapons by the outside -- Then that is a game changer because what that. Portends is potentially even more devastating attacks on civilians and did. It raises the strong possibility of those chemical weapons can fall into the wrong hands and get. Disseminated. In ways that would threaten US security or the security of violence in -- US military action fight game changer I mean that we. Would. Have to rethink. The range of options. That are available to us now -- as -- -- invested. In trying to bring about. Today. A solution inside of Syria. Obviously there are options that are available to me there on the shelf life that we have not. Deport. And that's spectrum of options. You know as. As early as last year asked. The Pentagon our military -- intelligence. Officials to prepare for me. What options might be available and I won't go into the details what those options might be. But. -- clearly. That would be an escalation. In our view of the threat to. The security of the international community our allies and the United States. And that means that there are some options that we might not other -- otherwise exercise. That we would. That we would strongly consider.

This transcript has been automatically generated and may not be 100% accurate.

Now Playing: Russia Faces Increased Tensions With the West After Sending Troops Into Crimea

Now Playing: Ben Affleck, John Kerry Take Part in Some Awkward Guy Talk

Now Playing: Attorney General Takes Stand Against Gay Marriage Ban

Now Playing: Couple Hopes Billboard Will Bring Taliban-Held POW Home

Now Playing: Joe Biden on 2016: 'Haven't Made Up My Mind'

Now Playing: Defense Secretary Announces Steep Cuts to US Military

Now Playing: President Obama Speaks to the National Governors Association

Now Playing: Jindal vs. Malloy: The Kumbaya moment of governors that turned into a partisan fight

Now Playing: {{itm.title}}

{"id":19075802,"title":"Obama Won't Commit to Military Action Against Syria","duration":"6:09","description":"The president says more investigation is needed on chemical weapons reports.","url":"/Politics/video/obama-will-not-commit-military-action-against-syria-19075802","section":"Politics","mediaType":"Default"}